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MICROBIO EX.19
Extracellular Enzymes
Question | Answer |
---|---|
Amylase | hydrolyzes substrate starch |
DNase | hydrolyzes DNA. |
Collagenase | hydrolyzes substrate gellatin |
Caseinase | hydrolyzes casein protein (milk protein) |
Lipase | hydrolyzes the breakdown of tributyrin (fat) |
Starch hydrolysis: result? interpretation? POSTIVE | after adding iodine, media turn purple (iodine detects starch by turning purple), but for POSSITIVE: colorless around growth because: Amylase seceted by organism, starch has been broken down and is no longer present in the medium surrounding the growth. |
Starch hydrolysis: result? interpretation? NEGATIVE | after adding iodine, media turn purple (iodine detects starch by turning purple), but for NEGATIVE: purple still around growth, because amylase is not secreted by organism. Starch has not been broken down and is still present in the medium surround growth |
What is DNA composed of? | Nucleotides. Nucleotides are joined together by phosphodiester bonds |
Result for DNAas positive? | Growth with red color. clear area surround the growth because organism has hydrolyzed DNA |
Result for DNase negative? | Area surrounding the growth is still green. Organism is negative for DNA hydrolysis. |
Positive for gelatin hydrolysis | Liquid after 24-48hrs: collagenase positive, fast gelatin hydrolysis Solid after 24-48hr: continue incubate up to 1 wk. Liquid after 1 wk: collagenase positive, slow gelatin hydrolysis. |
Negative for gelatin hydrolysis | solid after 1 week incubate. |
What does caseinase do? | Caseinase is an enzyme that hydrolyzes casein (protein in milk) into amino acid. |
Positive for casein hydrolysis | clearing surrouding growth |
Negative for casein hydrolysis | no clearing around growth. |
Positive for lipase | clearing arround growth. Growth could be blue tinge because lipase hydrolyzes tributyrin. |
Negative for lipase | no clearing. Lipase does not hydrolyze tributyrin. |